Poly-p-phenylenebenzobisthiazole, poly-p-phenylenebenzobisoxazole and poly-2,5-benzoxazole are intractable polymers by which is meant they are non-melting but soluble. Mixtures of these polymers have been made with thermoplastic polymers to provide melt-processability.
Fibrids of various polymers and their preparation are well known in the art (see Morgan, U.S. Pat. No. 2,999,788). The present invention provides a process for preparing fibrids from mixtures of the aforementioned intractable polymers and thermoplastic polymers, which are particularly suitable for production of papers and films thereof. The fibrids and the papers and films of such fibrids are new and possess unusual properties.